Sealing instruments of the specified type are used to perform operations on living human or animal patients. They are used to grip and seal tissue under the influence of pressure and current flow and also the resultant heat. In addition such instruments can be used to sever coagulated or sealed tissue.
US 2007/0078456 A1 discloses such an instrument having two movable branches, which are used to grasp hollow vessels. The two branches can be powered, such that the grasped and compressed hollow vessel is heated between the branches and the vessel walls are connected to one another. The vessel, which is closed and thus sealed in this respect, can then be severed in the sealing zone by means of a displaceable blade.
In order to seal the vessel, the two branches of the tool have flat contact surfaces, between which the vessel is sealed. The contact surfaces must have a considerable minimum width in order to seal the vessel reliably. The miniaturisation of such tools is thus subject to limits.
Furthermore, U.S. Pat. No. 6,113,598 A discloses an instrument having two branches, wherein one (the upper) branch has a strip-like protrusion, which fits into a groove in the lower branch, which is delimited by two resilient branch halves.
With such an instrument it is possible to resiliently clamp the vessel ends during coagulation. Here too, however, miniaturisation is subject to limits.
US 2002/0115997 A1 discloses an instrument that is intended in particular for the resection of lung tissue. The instrument has two branches, which can be moved towards one another and away from one another, with electrode structures on both branches. The electrode structures are profiled on either side of a cutting slit, through which a separating element can move, such that grasped tissue is held in a form-fitting manner and is sealed between the branches. Here, both the upper and lower branch on each side of the cutting slit contain a positive and a negative contact in order to produce the widest possible sealing edge on the tissue.
U.S. Pat. No. 8,394,094 discloses a similar electrosurgical instrument, in which the cutting electrode is assigned a spring-mounted abutment.